1. Field
One embodiment of the invention relates to a hard disc apparatus and head alignment method.
2. Description of the Related Art
A conventional hard disc apparatus adopts a track/head skew method. Upon completion of access to sectors on one track, a head is moved to the next track. In this case, the head is moved to a neighboring track on the same recording medium or to a track on a different recording medium having the same cylinder number. In consideration of a time required for this movement, sector positions on neighboring tracks are skewed.
For example, in Jpn. Pat. Appln. KOKAI Publication No. 4-146573 (from the 13th line of the lower left column to the 5th line of the lower right column, page 2, FIG. 3), a format map is created by reading a defect list recorded on a medium to obtain a defective sector in that track, and assigning sector numbers while skipping the defective sector. Next, a track skew value is set to be a value obtained by adding the number of sectors required for head switching and the number of alternate sectors used in the previous track, and subtracting the number of alternate sectors per track from the sum, and formatting is done to have, as the first sector, a position by skewing a sector position behind the first sector of the previous track by the track skew value. In this way, a track skew method that can minimize a disc rotation waiting time upon making a read or write access across tracks is provided.
On the other hand, defect processing which substitutes sectors not suited to read/write accesses due to a defect such as a scratch on the recording surface of a disc using a reserved area prepared in advance is executed. As an example of the defect processing, skip processing is known. In this processing, unrecordable sectors formed at the time of manufacture are registered in a primary defect list, and defective sectors registered in the primary defect list are skipped without being used upon recording of actual data. During this skip period, the head cannot access any sector. In the above patent publication, since the track skew is done, when the head continuously and sequentially accesses from a certain track to a neighboring track, a track moving time for the track skew is required. For this reason, when the skip processing is executed due to the presence of a defect, the time in which the head cannot access any sector is increased to the total of the skip time and track moving time.
As described above, in the conventional hard disc apparatus, when the skip processing for skipping a defect on the disc recording surface without using it upon recording data is executed, the total time of the skip time and the track moving time is a time in which the head cannot access any sector, and the data transfer rate and, especially, the disc transfer rate drop, thus deteriorating performance.